Driving of cinematographs and sound reproducing means in synchronism



May 9, 1933. J. H. T. ROBERTS DRIVING OF CINEMATOGRAPHS' AND SOUNDREPRODUCING MEANS IN SYNCHRONISM Filed Jan. 29, 1930 2 Sheets-Sheet, l

J55EPH Hmemso N THo MsoN RQBLRTS INVENTOR;

KL: Attorney.

May 9, 1933. I J. H. "r. ROBERTS 1,907,445

DRIVING OF CINEUATQGBAPHS -AND SOUND REPRODUCING MEANS IN SYNCHRONISMFiled Jan. 291 1950 2 Sheets-$heet 2 mung.

0 JZJsEPH HARRISONTHOHfiON ROBERTS" m v ENTOR:

Patented May 9, 1933 UNITED STATES PATENT OFFICE JOSEPH HARRISON THOMSONROBERTS, LONDON, ENGLAND, ASSIGNOR TO BRITISH TALKIESGOPE LIMITED, OFLONDON, ENGLAND, A COMPANY OFGREAT BRITAIN DRIVING OF CINEM ATOGRAPHSAND SOUND REPROD'UCING MEANS IN SYNCHRONISM Application filed January29, 1930, Serial No A to run in synchronism with'any type of gramophone.It is well known that one system of talking pictures is based upon thetaking of a film and the simultaneous taking of a gramophone record, therunning of the film and the turning of the record being in a definitespeed ratio to one another. For the reproduction of the talking film itis necessary to run the film through the pro gector machine and to playthe record upon a turntable, for example, a gramophone turntable, thespeed ratio of the projector machine (say in number of pictures passedper second) and the gramophone turntable (say in revolutions per minute)being the same as when the film and record were originally taken. Whenthis correct ratio of speeds is secured the rec- 0rd and film are saidto be synchronized,

A further object of this invention is to enable an em'stingcinematograph projector and an existing record rotating mechanism (suchas a gramophone) to be used in conjunction with one another withoutnecessarily placing these two devices in any particular positionalrelationship with one another. The two parts may thus be moved aboutpractically independently of one another without interfering with theaction of the coupling.

According to this invention, I couple the cinematograph projector andthe record rotating mechanism together by means of a shafting(preferably a flexible or jointed cable or shafting) which acts as acheck to maintain a definite speed ratio between the projector and therecord rotating mechanism. The said shafting is preferably provided atits ends with means whereby it may readily be attached to a suitablepart of the projector, on the one hand, of the record rotatingmechanism, on the other hand.

Further, according to. this invention I arrange that the record rotatingmechanism run u d r ow power h i it i p o- 42am, and in Great BritainMarch 7, 1929.

vided with motive power other than that which it may derive from the.linking device mechanism as distinct from any governor device associatedwith the projector.

I have discovered from my experiments that in order to ensure steady anduniform rotation of the record, in circumstances such as those mentionedabove (and particularly where a flexible cable shaiting is employed forthe linking device) it is very desirable to have as little power aspossible actually transmitted along the shafting (which is a reason forproviding the record rotating mechanism with its own motive 'powerirrespective of any power which may come to it via the synchronizinglink) and also to provide a governor in association with the recordrotating mechanism rather than 'in association with the projector. llfind that irregularities of motion are liable to arise in the projectorand in the linkage system and, even it a governor be provided at theprojector, irregularities may still occur in the linkage system; forthese reasons 1 have found it to be important (whether a governor isprovided at the projector or not) to provide a governor at the recordrotating mechanism itself.

it willhe seen from the foregoing that a very convenient and ready-maderecord rotating mechanism, having the features abovementioned, namely,its own motive power and a governor associated with it, is already tohand in the shape of any of the standard types of gramophone. Thereasons are. (a), the gramophone is already arranged for carrying arecord or equivalent, (5) the gramophone is equipped with a governor andis specifically designed and adapted for steady running, (0) thegramophone runs under its own motive power so that the connection linkbetween the gramophone and the projector may serve substantially as asynchronizing check and not mainly for the purpose of driving therecord, (d) the soundbox and tone arm of thegramophone, together withthe re roducin sound chamber, are already availa le, (e) i an electricalpick-up is to be used, this may readily be fitted to the gramophone. Itwill be seen, therefore, that according to my invention I attachconsiderable importance to the fact that the synchronizing devices whichI employ are, in appropriate forms, adapted to enable any existinggramophone to be used and synchronized with a cinematograph machine.

Step up or step down gearing may be introduced at any convenient pointof the synchronizing link inorder to obtain the desired speed ratio, asit will be readily appreciated that the rotational speed of any givenpart of the projector mechanism will not necessaril be the same as thatof any given part the record rotating mechamsm.

Other advantageous and novel features and constructions are provided bythis invention and will be more fully described in the followingdetailed description and claimed in the appended claims.

In order that my invention may be the more clearly understood andreadily carried into efiect, I will proceed to describe the same withreference to the accompanying drawings which illustrate byway of examplebut not of limitation certain convenient embodiments of the invention inwhich Figure 1 is an illustrative view showing a certain type ofprojector and a gramophone coupled together by means of a flexile cablecontained within a flexible outer casing according to this invention.

Figure 2 is a view of one end of a flexible cable according to thisinvention showing one method of connecting the same to the pro'ectormechanism.

igure 3 is a view partly in section showing the gramophone end of thecable and the means for coupling the same to the gramophonel Figure 4 isa plan view of a particular type of separate turntable which may be usedac-- cording to this invention.

Figure 5 is a grspective view of a certain type of bra et adapted to besecured upon the cabinet of a gramophone and to carry or support theouter casing of the flexible cable.

Figure 6 is a view showing another form of construction of thesynchronizing link acco to this invention. I

Referring now to Figures 1 to 5 of the accompanyingndrawings, A is acinematograph pro ector w 'ch may be of any suitable type, thisarticular projector having a stand or 9 base in which bolts are providedcarrying nuts B Under one of the sets ofnuts' is secured a bracket Chaving an upwardly groje'cting arm C carrying a slanting tube This tubeD is provided at its upper,

end with a small casing (see Figure 2) within which are journalled bevelgears E and E, the one E being secured to a horizontal shaft E (whichpasses out of the casing and is secured to a length of flexible orjointed shaft E having at its free end a pulley E. To connect the deviceto the projector, oneof the vpulleys in the same (with which the pulleyE is identical) is removed,

and the pulley E placed in its position; the driving belt is then placedover the pulley E and it will be seen that as the projector runs, thebevel gearing E and E will be ro tated. Secured to the bevel wheel E isa flexible cable F which rotates inside a tube D and after passing outof the tube D, rotates inside the flexibletube G which is secured to theend of the tube D by means of a union G This cable F, with its outerflexible tube or casing G, is of the type which'is sometimes known asflexible shafting and is commonly used for such purposes as the drivingof speedometers, dental drills and so on.

The-cable F and the tube G are of the desired length to correspond tothe maximum distance apart at which it is desired to use the gramophoneand the projector, andat the end remote from the projector the cable iscoupled to the gramophone H. A bracket J (see Figures 1 and 5) isprovided to support the cable and to prevent the same from contactingwith the record. This said bracket preferably comprises aplate J slottedas at J 2 to allow a U-shaped clamp J 3 to slide up and down the same.The. clamp J 3 is placed over the upstanding edge of the amophonecabinetand is clamped thereto y means of the clamping screw J With theclam J firmly secured to the gramophone ca inet, the height of the upperend of the plate J can be adjusted by a slackening of the locking nut Jand then tightening the same when the plate J has been adjusted to thedesired position.

In the case of a ophone of the portable type in whic there is noupstandingedge I use a bracket of a somewhat different type. The plate Jis still employed but the,

part J is made suitably larger and is placed in a vertical position sothat it reaches from 4 the top to the bottom surfaces of the cabinet,

pressing downwards on the top surface, up-

wards on the under surfaoe'of the cabinet and passing from top to bottomalongtheside of the cabinet; the screw J is in this case preferablyplaced in the upper limb of the 0 amp so as to screw down upon the topsurface of the gramo hone cabinet.

At the upper end with a stirrup J to receive the outer tube or casingG-of the cable F and a clamping e plate J is provided I nut and bolt Jare provided to hold the same firmly within the stirrup.

venient to make any ready mechanical con- As it is impossible or, at anyrate, inconnection to the centre pin of an ordinary gramophoneturntable, I prefer to employ, according to my invention, a separate oradditional turntable which carries certain features which are convenientfor the carrying out of the invention. This separate turntable may beplaced in position instead of the standard turntable of the gramophone,the latter being removed and the former substituted. As, however, thecentre spindles of gramophone motors vary considerably this is notalways a convenient method and I prefer in practice to use a separateturntable which is additional to the standard turntable of thegramophone and which is placed upon the same exactly as a record isplaced in position. This separate turntable has a centre hole of thesame size as the standard hole in the centre of a record and is,therefore, adapted to be placed upon the standard turntable andaccurately located with the standard centre pin. The additionalturntable, however, carries at its centre a pin which is in generalsubstantially longer than the standard pin ofthe standard gramophone-turntable, which pin is adapted (by having a non-circular part orotherwise) to engage with the terminal of the synchronizing link as willbe described presently.

In Figure 4 is shown one particular form of this separate turntable inwhich the turntable is of spider formation. This form has the advantagethat for a given total mass the moment of inertia of the turntable iscompartively low. I find this convenient for the following reason: Whenthe projector and the gramophone are in operation and the motive poweris switched off there is a tendency (particularly if the projector isdriven electrically and the gramophone driven by a spring motor) for themomentum of the standard gramophone turntable, together with the.additional turntable which it is carrying upon it, to throw a torsionalload upon the synchronizing cable. Clearly the smaller-the moment ofinertia of the separate or additional turntable, the smaller will bethis sudden torsional load when the apparatus is switched oil. At thesame time I do not confine myself to a separate turntable of the typeillustrated but may use any form of loose alternative or additionalturntable or spindle which is adapted to fit upon the standard turntableand carries the special features which I require.

In Figure t the turntable is of spider formation and has a number ofarms K with spatulated ends K provided on their upper faces with rubberor like pads K One of the arms K is provided with an extension K thepurpose of which will be referred to hereinafter. The turntable isprovided with a central pin K having a squared upper end K the pin K, atits under part, being suitably bored out to engage with the centre pinof the gramophone.

The end of the tube G remote from the projector terminates in a casing Lto which it is secured by means of a union Gr and the flexible cable Fis provided at this end with a squared socket to take over the squaredend M of a spindle M journalled in the casing L and having a bevel wheelM engaging with a further bevel wheel M journalled in the casing, thespindle M of the bevel wheel M being bored out as at M to receive thecentral pin K of the special turntable. The upper end of the bore M issquared as at M to receive the squared end K of the pin K end, ifdesired, a clamping screw M may be provided for still further security.The bevel wheel M" is (in the case illustrated) of larger diameter thanthe bevel wheel M so as to give in this case a stepdown gear ratio.

The gearbox shown in Figure 3 is attached to the end of the casing ofthe flexible cable by means of a suitable union joint so that anygearbox may be readily removed and another similar gearbox, but ofdifferent gear ratio, substituted in its place.

In'use, therefore, with this form of the invention, the separateturntable is placed upon the standard turntable of the gramophone, therecord N (see Figure 1) is placed upon the loose turntable and the box Lis then placed over the pin K" which will slide along the bore M andbecome held against relative rotary movement therewith when the squaredend K engages with the squared portion M of the bore.

Consider now the operation of the device. With the projector andgramophone ready to start and the flexible cable duly connected up, thetwo mechanisms are switched on and run each under its own motive power.(In the case of a spring driven gramophone motor this can be released sothat it is always ready to start but it will, in fact, be unable to moveuntil the projector starts owing to the flexible cable link holding itstationary; the moment the projector is switched on, however, the

spring driven gramophone motor is able to operate.) The pulley IE will,of course, rotate due to the Working of the projector and will rotatethe flexible cable F. This rotation will be transmitted throughtheflexible cable and the gearings to the central pin of the specialturntable which is placed upon the standard gramophone turntable andwill tend to rotate both turntables together as a whole (owing to thefrictional engagement between the special turntable and the stand ardturntable).

If it so happens that the speed of the projector and the speed of thegramophonefirrespective of any action of the flexible cablesynchronizing link) bear the required ratio to one another then theflexible cable is rotat ing idly, but in general this condition will notobtain and the natural s eeds of the projector and the ramophone wi 1not bear the correct ratio. he flexible cable link will, however, act totransmit power from whichever device tends to run too fast, to whicheverdevice tends to run too slow, the result being in any case that theprojector and the gramophone are bound to turn in the proper speed rationo matter how fast or how slow the actual speed may be.

Of course. the two ends of the flexible check cable, according to thisinvention, may be connected to the projector and the gramophone at anyconvenient point, either removably or not. Thus the flexible cable mayat one end be provided with a gear wheel gearing with a suitable gearwheel in the gramophone mechanism.

i The object of the projection K on the special turntable is as follows.When placing a record in position it may be necessary to rotate therecord by hand to bring it to a definite position and the projection(which will protrude from under the record) forms a convenient means oftaking hold of the special turntable and holding it stationary whilst.the record is shifted. At the same time if one of the flats on thesquare part M of the centre pin (see Figure 3) is arranged to face inthe same direction as this projection K then it is convenient to makethe gearbox (Figure 3) engage with the centre ,pin K (Figure 4) bypulling the special turntable around until the projection K is pointingin the same direction as the locking screw M (Figure 3). In thisposition we know that the flats of the centre pin K (Figure 4) areparallel with the flats of the squared portion M (Figure 3) of thesleeve of the gearbox.

According to a modification, instead of employing right angle bearingsas at E E M and M I may connect the flexible cable direct to theprojector mechanism or to the turntable or gramophone mechanism, itbeing bent round in a suitable curve or sweep.

The central pin of the special turntable may be of any non-circularshape in order to enable the flexible cable to be attached theretowithout departing from the spirit of this invention.

Referring nowto Figure 6, the flexible check device illustratedthereinis similar to that illustrated in Figures 1 to 5 except that instead ofemploying a stepdown gear ratio at the gramophone end of the flexiblecable I provide a box or casing N which may be provided with adownwardly projecting slotted bracket N by means of which the gearbox orcasing may be mounted in position on the gramophone cabinet and at thesame time will serve to support the flexible cable and its flexiblecasing. Within this gearbox N are arranged two (or more) unequal spurwheels, two wheels being shown at O and O by means of which the desiredgear ratio is obtained. This figure also shows a form in which the rightan le aring at the projector end of the flexib e ca le is dispensedwith. The right angle at may also (as stated above) be dispensed with atthe gramophone end of the cable. In Figure 6, however, I have shown asmall gearbox P (with cover removed) at the gramophone end with a 1 to 1bevel gearing Q to give the desired right angle bend to the linkage. Itwill be clear that where these bevel wheels are made unequal this servesthe purpose not only of the right angle bend but also of the stepdowngearing in which case the gearing and gearbox shown at N", O, 0 (Figure6) are unnecessary. The other parts of the device are similar to thoseillustrated by or described in connection with Figures 1 to 5.

In order to avoid the need for disengagin the flexible cable attachmentfrom the specia turntable when placing a record in position or removingthe record, I may provide a horizontal disc (equivalent to a turntableand adapted to carry the record mounted upon the upper extremity of thecentral pin of the special turntable). In this way we have a specialturntable (or equivalent) below, resting upon the standard turntable orspindle of the gramophone, the horizontal disc (to which I have justreferred) is above, whilst the flexible cable terminal gearbox issandwiched between the two and is pierced through its centre by thevertical pin connecting the lower and upper discs, this pin, of course,projecting a small distance above the upper disc. In this way it is onlynecessary to place the record upon the top of the upper disc (preciselyas though this were an ordinary standard gramophone turntable) and theflexible cable terminal gearbox does not need to be interfered with.

By a modification of the arrangements which I have previously describedit is possible to doaway with the need for a loose or separate turntablealtogether. In this form of the invention I provide at the under surfaceof the flexible cable terminal gearbox a circular horizontal disc(mounted, of course, so that it rotates with the horizontal gear wheelinside the gearbox) this disc being roughly two or three inches indiameter (approximately the size of the blank or unrecorded space in thecentre of the gramophone record) and having a central hole adapted toengage with the central pin of the standard gramophone turntable. Theunder surface of this disc (that is the surface which contacts with theupper surface of the record) may be covered with rough india rubber orotherwise coated or adapted so as to engage frictionally with the uppersurface on the gramophone record upon which it rests and, furthermor thei m y be of sufli i nt' weight (or sufiicient'weight may otherwise beadded) to make it press sufliciently firmly upon the surface of therecord. To use the invention in this form, the record is simply placedupon the standard turntable in the ordinary Way and then the flexiblecable with weighty terminal gearbox is brought into position and theterminal gearbox is placed upon the top of the record engaging with thatpart of the central pin which projects through and above the record. Inthis way the standard turntable, the record, and the terminal gearboxare linked together purely by friction.

In general, I find that in adapting this invention to various types ofprojector machine, the wheel or other rotating member which is mostconveniently accessible on the projector, rotates at a considerablyhigher speed than the normal speed of the gramophone turntable. Thisbeing the case I find it preferable in practice to place the stepdowngear as near as possible to the gramophone end of the cable so that, forthe greater part of its length at any rateif not indeed for the whole ofits Iength the cable is rotating at the highest available speed. Thehigher speed of rotation of the cable means the smaller torque andconsequently enables me to use a cable of the minimum diameter. Aparticular form to which I wish to give special prominence and which Ihave used very satisfactorily in practice, is to have the flexible cablerotating at the same speed as the projector member to which attachmentis made, this speed being maintained right up. to the point where thecable is attached to the centre of the gramophone turntable (or where itenters the terminal gearbox engaging with the centre of the gramophoneturntable). The right angle bevel Wheels, which are then used to linkthe horizontal flexible shaft with the vertical driving pin at thecentre of the turntable, are of use a step up gear at the projector orindeed I may use an extra degree of step up ratio and then step downagain at the gramophone end.

In the foregoing specification I have described how the gearing may beintroduced at any point of the checking link or how it may be locatedentirely at one end or the other. There are several advantages in havingthe gearing entirely at one or other extremity and one of theseadvantages is as follows. Let us assume the gearing is located in thegearbox at the gramophone end net and which carries or supports thecable casing). This distance will vary with different gramophones. If mycable casing is uniform there is nothing to prevent me from pulling thecable and easing through the stirrup J (Figure 5) until a suflicientlength is passed through to enable the extremity of the link to reachthe centre of the turntable. On the other hand, if the gearing iscontained in a gearbox at some intermediate point of the cable, as shownin Figure 6, it is virtually essential to locate this gearbox eitherupon the grainophone or upon the projector and this at once imposeslimitations of dimensions and position which may be very inconvenient.Therefore, it is very convenient as already mentioned to have thetubular casing free and unencumbered so that the supporting bracket cangrip or embrace it at one point just as well as at another.

I have referred in the foregoing specification to the terminal gearbox L(Figure 1 and F igure 3) being attached to the extremity of the flexiblecable by means of a simple union oint so that it can be readily removedand another gearbox (with a different gear ratio) substituted. Theadvantage of this is that if at any time it is desired to employ a filmand a record in which the speed ratio is different or if the device isto be used with 1 a projector in which the speed of the accessiblerotating member renders a different gearing necessary, it is a matter ofa few moments only to remove the terminal gearbox L and to substituteanother having the required gear ratio.

In the foregoing specification I have described a bracket (see Figure 1)which is secured to the projector and carries or holds theflexible cableor its casing. It will be understood that this bracket is adapted to theparticular type of projector in question; the bracket will naturallytake diflerent forms for diiferent types of projector, being designed tobe secured readily upon some conveniently available part of theprojector or by conveniently available screws. Its purpose, however, issimilar whatever particular form it may take.

In Figure 2 is shown (E) a short length of flexible cable or shaftingwhich links between the rotating member of the projector to whichconnection is made, on the one hand, and the part of the synchronizinglink which is supported by the bracket ab ve. referred to on the otherhand. It will be clear that unless some degree of flexibility isintroduced in this way the bracket wil have to be ve accurately adjustedso as not to in tr uce undue stresses into the system. By havin the partE flexible, however, any small egree of mal-adjustment of the bracket isof no serious consequence since it is taken up by this flexible member.I consider this an important feature inasmuch as the device is intendedin certain forms for home users who cannot be expected to haveengineering knowledge or to make accurate adjustments. Of course, theflexible member shown at E is by way of illustration; it may be a lengthof flexible cable or any jointed or other equiv alent.

The application of this invention to the cinematographic camera andassociated recording machine is equally valuable since it overcomes oneof the difficulties at present experienced in this field due to the factthat the cinema camera has to be moved about whilst it is desirable tokeep the recording turntable machine in a fixed position. Hitherto therecording machine and the camera have been mounted upon a cumbersometrolley which is extremely inconvenient. By my invention this difficultyis overcome.

I claim 1. Means for synchronizing a cinematograph machine and aphonograph machine separately driven, comprising a flexiblesynchronizing shaft having a gearbox at either end, a device adapted torest upon the turntable of the phonograph machine and to carry therecord upon the upper surface of said device instead of upon thephonograph turntable, said device being provided at its under part witha hole adapted to fit over the centre pin of the phonograph turntable,and its upper part with an upstanding central peg adapted to passthrough the hole in a standard phonograph record, said peg being of sucha shape as to enable a positive connection to be made between said pegand the end of said flexible synchronizing shaft.

2. Means for synchronizing a cinematograph machine and a phonographmachine separately driven, comprising a flexible synchronizing shafthaving a gearbox at either be made between said device and said flexibles nchronizing shaft.

3. cans for synchronizing a cinematograph machine and a phonogra hmachine separately driven, comprising a exible chronizing shaft having agearbox at eit er end, a device adapted to be substituted for theturntable of the phonograph machine and to carry the record upon theupper surface of said device, said device being provided at its underpart with a hole adapted to fit and enga e with the centre shaft of thephonograp machine and at its upper part with an upstanding central pegada ted to pass throu h the hole in a standar phonograph recor said pegbeing of such a shape as to enable a positive connection to be madebetween said peg and the end of said flexible synchronizin shaft.

4. Means or synchronizing a cinematograph machine and a phonogra hmachine separately driven, comprising a exible s chronizing shaft havinga gearbox at eit er end, a device adapted to be substituted for theturntable of the phonograph-machine and to carry the record upon theupper surface of said device, said device bein provided at its underpart with a hole apted to fit and engage with the centre shaft of thephonograph machine and at its upper part with a central hole adapted toreceive a peg secured to the end of said flexible synchronizing shaft,said peg being of a size adapted to pass through the hole in astandardphono' graph record and of such a shape as to enable a positiveconnection to be made between said device and said flexiblesynchronizing shaft.

In testimony whereof I have signed my name to this specification.

JOSEPH HARRISON THOISOI ROBERTS.

end, a device adapted-to rest upon the turntable of the phonographmachine and to carry the record upon the upper surface of said in astandard phonograph record and of such a shape as' to enable a positiveconnection to

